SX-780 score... which pots are for DC offset?

jpciii

I like pizza
Scored a SX-780 for $7.50 at a local auction house tonight. :banana:

It a little dusty, but otherwise in excellent condition looks-wise. All the bulbs work and all the controls are static-free too. Sweet.

DC offset measures -75mv and -98mv. Not sweet. Caps look good and it works, but I want to know which pots are for adjusting the Offset.

I see a couple of white ones in front-left near the relay and a couple of blue ones right in the middle of the unit. There are more pots in the back on the tuner board, but I assume that those are for the tuner...

Any help is appreciated.

Thanks, John.
 
The ones close together near the left front are for meter calibration. The other two, at the left and right closer to the middle of the board, are for offset.
 
Nice score John! It's about time something decent turns up in that "not so decent" town. Congrats. Let's see some pics and hopefully you can get that DC under control. How does this score affect the SX-727 placement? It will be interesting to hear your thoughts on the comparison of the two. :thmbsp:
 
Well, I was totally wrong about the clean controls. They will be getting some attention. The tuner is pretty far out of alignment, but it picks up stations well. DC offset is now dancing between -1.2mv and +1mv on both sides. I'll check it again after it settles and I clean it up. Those pots sure are sensitive!

Crotalus,
Nice ad, dude! Did that come from one of your very special magazines?
The wife gives a cheerful "Loook, Blue!" or "Ooohh, pretty" whenever we turn on your old SX-727 and she gazes lovingly into the blue-lit faceplate. She digs it in the TV room. We had it on tonight while American Idol was on.
** hangs head in shame for watching American Idol **
I don't think the 727 is going anywhere soon. And thank you for recognizing what a VERY RARE occurrence it is to find a piece of vintage audio in this town! (He used to live here)

After I get it all cleaned and what-not, I'll give my impressions and post some beauty shots for you guys.
 
Excellent, crooner. Thanks!

There are many SX-780 owners here, so hopefully this thread will prove usefull for everyone else too.
 
jpciii said:
Excellent, crooner. Thanks!

There are many SX-780 owners here, so hopefully this thread will prove usefull for everyone else too.

Absolutely! I am glad to help.

Enjoy the SX-780. I always keep one around. Indispensable.
 
What I don't understand, is why I can't find any SX-780's in Europe. The most popular higher end x80 series receiver that can be found here is the 980, but it seems the 780 provides more than adequate power and excellent sound while being much cheaper than the 980!
 
I think you can get those parts cheaper in the US than in Europe. Seems that those gear are more seldome here, or pepole are willing to give more money. Maybe the truth is somewhere in the middle.
 
Well, here it is. Not the best pic, but you get to see it in its natural habitat.

I think that something is up with the amp section. The right channel is just a wee bit quiter than the left. I also noticed that one of the big caps has a slight bulge in the top (I didn't notice it when I started this thread...). Are they related?

I would like to have this one running at peak performance since it is so clean. It also sounds pretty nice with a turntable and CD. I really like the sound I'm getting from it in my headphones, too.

thanks,
John
 
jpciii said:
I think that something is up with the amp section. The right channel is just a wee bit quiter than the left. I also noticed that one of the big caps has a slight bulge in the top (I didn't notice it when I started this thread...). Are they related?
Probably not.

The 780 has an 'inexpensive' volume control...it probably isn't tracking L-to-R very well...or else you've still got some crud in a switch or pot.
 
Thanks, EW. I shot the controls with some cheap cleaner before I ever listened to it. Maybe I should open my wallet and get some DeOxit and ProGold. I fiddled with the volume and balance pots and also fiddled with the stereo/mono switch tonight, and both channels are even now. I think they need to be cleaned again. When I get the Caig stuff, I'll have to take it apart again.

I'm really liking the sound of it. I've been A/B testing it against my Marantz 2265B through HPM-900's (quietly, it's late) and my Grado headphones. The Marantz has a more controlled bottom but sounds somewhat muffled or muddy compared to the 780. The Pioneer has more "sparkle" and clarity up high. Tomorrow, I'll get to crank them through the speakers and see what's up.

New toys are fun!
 
She sure does look pretty John. I didn't realize until I saw your pic, that the 780 has only one tuning meter. But just staring at the thing....it's just's the simplicity of it all that makes it beautiful. Like staring at a Ferrari. :yes:
 
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